CBP/P300-LIKE HISTONE ACETYLTRANSFERASE, HAC1, INTERACTS WITH FCA TO CONTROL FLOWERING TIME IN ARABIDOPSIS

Abstract

In Arabidopsis thaliana, the floral transition is tightly controlled by a network of pathways, including photoperiod, vernalization, thermosensory, gibberellin and autonomous pathways, in response to various environmental and endogenous flowering signals. Here we report that HAC1, previously known as a CBP/p300-like histone acetyltransferase, interacts with FCA in the autonomous pathway, thus affecting the expression of a central flowering regulator, FLOWERING LOCUS C (FLC), to control the floral transition. Loss of function of HAC1 results in a late-flowering phenotype associated with FLC upregulation. Consistently, flc suppresses the flowering defect of hac1. We further show that HAC1 interacts directly with FCA in the nucleus and mediates acetylation of FCA. Our results suggest that HAC1 plays a hitherto unknown function in acetylating FCA, thus affecting FLC mRNA levels during the floral transition.